1. Field of the Invention
The present invention relates to the field of telecommunications. More particularly, the present invention relates to a method and a system for acquiring and tracking frame boundaries of a received Discrete Multitone (DMT) signal in a DMT system.
2. Description of the Related Art
In conventional Discrete Multitone (DMT) modems, long pseudo-random (PN) sequences and correlation computations are used for timing acquisition and for tracking. The long sequences used result in a high implementation complexity, as well as an increased overhead and signal processing delay associated with both call setup and data transmission. The PN sequences are first encoded into discrete tones, and then are transformed using an inverse discrete Fourier transform into time-domain samples for transmission. The received samples are Fourier transformed to reproduce the PN sequence, and then are correlation tested for identifying frame boundaries. Channel estimation, which is used for coherent signal detection, is done only during call setup and requires separate PN sequences. Consequently, subsequent signal detection is susceptible to clock drift.
What is needed is an efficient and effective technique that can be used with DMT modems for joint timing recovery and channel estimation.